The 2-amino-4-(pyridinyl)phenols used herein as intermediates are disclosed inter alia, as cardiotonics and claimed per se and as cardiotonics in copending U.S. Application Ser. No. 170,896, filed July 21, 1980, now U.S. Pat. No. 4,297,363, issued Oct. 27, 1981.
(a) Field of the Invention
This invention relates to (pyridinyl)benzoxazol-2-(3H)-ones, their preparation and their use as cardiotonics.
(b) Description of the Prior Art
Coates et al [J. Chem. Soc. 1943, 409] show the preparation of 4-(2-pyridinyl)-2-aminophenol in four steps from N-acetyl-4-(2-pyridinyl)aniline, the last two steps comprising converting 2-nitro-4-(2-pyridinyl)aniline to 2-nitro-4-(2-pyridinyl)phenol and reducing the latter to convert nitro to amino. Coates et al also show 3-(4-pyridinyl)phenol. Coates utilized said pyridinyl-phenols as intermediates to prepare pyridinyl-quinolines, which in turn were investigated for possible spasmolytic activity with disappointing results.
Heilbron et al [J. Chem. Soc. 1940, 1279] show as intermediates in the preparation of 3- and 4-pyridyldiphenyls the following compounds: .beta.-3-aminophenylpyridine, .beta.-4-aminophenylpyridine and .gamma.-4-aminophenylpyridine and the N-acetyl derivatives of each, including the hydrochloride salt of .beta.-4-acetamidophenylpyridine; these three aminophenylpyridines currently are named 3-(3-pyridinyl)benzeneamine, 4-(3-pyridinyl)benzeneamine and 4-(4-pyridinyl)benzeneamine, respectively, the two 4-(pyridinyl) isomers used as intermediates herein.